In recent years, in order to solve problems such as a shortage of pathologists and remote location medical care, importance of diagnosis performed using pathological specimen images is increasing. The pathological specimen images are acquired by a microscope including an electric stage or a medical slide scanner (hereinafter referred to as microscope imaging system). However, it is necessary to overcome a large number of technical problems in order to acquire highly accurate images fit for diagnosis.
As one of the technical problems, a problem concerning stitching of images is known. A range of a specimen that can be imaged by an objective lens of a digital microscope is small compared with the entire specimen and is usually equal to or smaller than one hundredths of the specimen. Therefore, in order to acquire image data of the entire specimen, it is necessary to dividedly image the specimen a plurality of times while changing positions (divided imaging) and stitch an obtained plurality of image data.
Partial image data acquired in one imaging (hereinafter referred to as tile) is acquired while the while moving a specimen at a fixed interval at a time using an electric stage. However, positional deviation is caused by the influence of backlash of the stage or the like and an image is affected by the positional deviation. As a result, when tiles are simply arranged, a difference occurs in stitches. Image data representing the entire specimen (hereinafter, “entire image”) is not obtained. Therefore, in general, tiles are acquired such that peripheral sections of tiles adjacent to each other overlap. An entire image is formed after positional deviation correction is performed to match the shapes of overlapping places. Correction of distortion aberration of an objective lens, rotation of an image, and the like is also performed.
When the entire surface of one pathological specimen is imaged, the number of tiles acquired by a microscope imaging system exceeds one thousand (in the case of 20 million pixels/one tile). Therefore, there is a demand for an increase in speed of the stitching.
In a stitching method in a document scanner disclosed in Patent Literature 1, components in a document is imaged avoiding a blank segment in the document and only the components are stitched to attain an increase in speed.
In an editing method for a plurality of images disclosed in Patent Literature 2, partial image data sent from a server is reconfigured into an entire image on a PC. In this method, making use of the fact that the positions and the sizes of partial images sent to the server are known, reconfiguration processing is executed in a waiting time in arrival of the partial images at the PC to increase speed.